I wouldn't call it linear, actually. There's definite resistance before the dome collapses, but it's further down in the keystroke than in Cherry MX. The sound is also different: lower-pitched and quieter, with a "thock" on the upstroke as the slider hits the switch housing.

I have the Royal Kludge RC930-87 drop from a while back (it's a Topre clone keyboard) and I absolutely love it. I love it enough that I'd like to get a genuine Topre board for home and replace my Cherry MX Brown Coolermaster QFR I have at work with my Kludge.

In a related thought, I know Topre was asking about some novelty kepcaps / modifiers recently. Perhaps they (or Leopold) would be interested in doing a special edition cap set for a Massdrop FC660C? Would it be too much to ask for some spherical keys on a 660? :-3 Maybe the community would dig some vintage beige-style caps? Who knows, I think it'd be worth a shot.

You know what I'd really love to see? An FC660C with Novatouch sliders, so I could put Cherry MX keycaps on it.

Anyway. The FC660C has my vote, followed by the very cool-looking HHKBP Japan edition.